how to judge an element's previous or next element exist with jquery?
element, jquery, jquery-selectors
Solution
A jQuery selection will always evaluate to boolean `true` (as in an `if` statement). This is because it is not a native Javascript type -- it is an object.
You need to check the `length` property of the selection. If it is empty, this will be `0` and will evaluate to `false`, so the `if` will not pass. If it is not empty, it will be a positive integer and will therefore evaluate to `true`, so the conditional will pass.
if ($("li.test").next().length) { …… }
Problem
suppose I have an `<ul>` : ``` <ul> <li></li> <li></li> <li class="test"></li> </ul> ``` How can I judge the `.test` have its next element with jquery ? like this?: ``` if ($("li.test").next()) { …… } ``` the strange thing is that ,even I write like above: ``` if ($("li.test").next()) {alert("true");} ``` it still alert "true",but as you see,there is no element next to it ?why this happened? Or what I can do is ``` for (i = 0; i < $("li").length; i++) { if ($("li").eq(i).hasClass("test")) { if (i == $("li").length - 1) { alert("true"); } } } ``` presently this could solve my problem,but is there a easy way? thank you